I would look for someone else also. If they cannot meet that basic first deadline, it may be a sign of things to come (speaking from experience).

We can't quite tell, without being in the situation. You'll have to make the call. Sure, it's not a promising sign but we're looking at it in isolation. What's your gut feeling? How's contact between you and them been? Do they come off as genuine and is their work good, are they evasive and placatory? Business is business but people are also people. And things do happen.
With no disrespect to CP, I disagree. The main guy on our project lost his mother recently, things were delayed a bit, no big deal. I'm not saying it's not an excuse, I'm saying it might not be. We all have dofferent experiences and you have to judge yours, op, we can't.
However, the least I'd expect, if delays were indeed justifiable, is an indication of how long you're delayed by, & when you can expect the work. Without this, there's a bigger chance they're stringing you along.
I don't know how things work where you are, but around here you get little done during the month or more heading to the year end, and it would make sense to see whether things work out with them, and if they don't, look at other options next year, not now.

Yes, find someone else. If they can't even meet the first deadline, just think of the world of hurt you will be in 2 years from now.

You paid a builder for his services. He hasn't completed his services. Has he been in contact with you to keep you advised of the project schedule and any challenges he faces?

Thank you everyone, the death was not something the builder could've seen coming. He's a very family oriented guy so I'm giving him a pass this time. I heard back from him today with everything I needed.

90 days is sufficient time for all due diligence to be completed. You should have a preliminary plan and construction cost estimate in hand. If not, look for a more responsive builder.